VI. Immersing One's Head in Water
1617. If a fasting person intentionally immerses his entire head into water, even if the rest of his body remains out of water, as per obligatory precaution his fast is void. However, if a person immerses his entire body into water while leaving a small part of head out of water, his fast does not becomes void.
1618. If a person immerses half of his head into water once, and the other half the second time, so that his complete head was never immersed into water, his fast will remain in order.